Judgment, Supreme Court, New York County (Shirley Finger-hood, J.), entered September 19, 1989, denying a petition to annul a determination which had denied an application for accidental disability retirement, unanimously affirmed, without costs.

An accidental disability, for purposes of pension and retirement (Administrative Code of City of New York § 13-252), must meet the commonsense definition of a sudden and unexpected event (Matter of Lichtenstein v Board of Trustees, 57 NY2d 1010, 1012), as opposed to an injury resulting from routine performance of duty (Matter of McCambridge v McGuire, 62 NY2d 563, 568). It is the precipitating cause of the injury, rather than the job assignment at the time, that determines entitlement to accidental disability benefits (Matter of McCambridge v McGuire, 62 NY2d, supra, at 567).

Petitioner was injured when he stepped off a curb onto a cobblestone roadway. The only contemporaneous reports of the incident (the separate line-of-duty investigation and its accompanying medical evaluations) made no mention of any hazardous condition (cf., Matter of Pratt v Regan, 68 NY2d 746; Matter of Knight v McGuire, 62 NY2d 563). Unauthenticated photographs of the scene, as well as unsworn, self-serving statements by petitioner’s companions, submitted fully a year and a half after the incident, were properly given minimal weight. Respondent Board of Trustees’ determination by tie vote, resulting in ordinary disability retirement (Caruso v [*543] New York City Police Dept. Pension Funds, 72 NY2d 568, 573), can only be disturbed if entitlement to greater benefits can be shown as a matter of law (Matter of Canfora v Board of Trustees, 60 NY2d 347, 352). Concur—Murphy, P. J., Carro, Wallach, Kupferman and Asch, JJ.